1. Technical Field
The present invention relates to a projector.
2. Related Art
Recently, a projector provided with a vertical alignment (hereinafter, also referred to as VA) mode liquid crystal light valve, in which contrast when viewed from the front side is excellent, has been proposed. In the VA mode liquid crystal light valve, a liquid crystal layer having negative permittivity anisotropy is interposed between a pair of substrates, and liquid crystal molecules are aligned in a substantially vertical direction in a state where voltage is not applied. However, even when such a VA mode liquid crystal light valve is used, contrast is decreased and display quality is decreased when viewed from an oblique direction.
In the related art, compensation of the phase difference of light obliquely passing through the liquid crystal layer is performed, using a phase difference compensation element having an optical axis along a thickness direction, a so-called C-plate. In this case, the C-plate is obliquely disposed such that the optical axis of the C-plate is parallel to a pre-tilt direction of liquid crystal molecules, to compensate the front side phase difference of liquid crystal by the C-plate. In this case, a fixture for disposing the C-plate in an oblique posture is necessary.
However, when positional disclination (disclination of inclination angle) of the oblique fixture or disclination of an orientation angle of liquid crystal alignment occurs, it is difficult to perform sufficient phase difference compensation only by inclining the C-plate. When a gap occurs in a cell thickness of a liquid crystal panel, it is necessary to adjust the front side phase difference of the liquid crystal panel with the inclination angle of the C-plate. However, in this case, an effective retardation of the C-plate deviates from the optimal condition, and it is difficult to perform the sufficient phase difference compensation. As the pre-tilt angle of the liquid crystal molecules gets larger, the inclination angle of the C-plate gets larger. However, a difference of reflexibility between P-polarization light and S-polarization light in incident polarization light occurs, and the axis of the incident polarization light deviates to decreases the contrast.
It is proposed that higher phase difference compensation is performed using a phase difference compensation element having biaxial refractive index anisotropy in addition to such a C-plate, a so-called O-plate, to raise the contrast (for example, see JP-A-2009-145862).
In the projector described in JP-A-2009-145862, the C-plate and the O-plate are disposed on the light emission side of the liquid crystal panel. However, merely by disposing the C-plate and the O-plate on the light emission side of the liquid crystal panels for red light modulation, green light modulation, and blue light modulation, a phenomenon in which black display becomes slightly bright, so-called black floating occurs, and thus it is difficult to sufficiently improve the contrast.